Life history and Ageing in the Wild

为什么我们以及所有其他生物会随着年龄的增长而逐渐退化，并更有可能死亡，这一研究几乎与生物学中的其他所有问题都有关联。然而，绝大多数的衰老研究关注的是功能下降的机制解释。对于衰老发生的原因，我们在功能上的解释仅仅触及了表面，而对于自然种群中衰老的过程，我们更是一无所知。我们需要了解野外的衰老过程，因为很明显，自然界的衰老过程将影响关键过程的动态，比如性选择和生命史的进化。昆虫构成了动物生物多样性的绝大多数，并在实验室中得到了深入研究，它们已成为理解衰老的重要模型系统。然而，似乎很有可能的是，当它们离开一个食物无限、没有寄生虫或捕食者的环境时，昆虫可能会表现出不同的衰老模式。现在很清楚，即使是短命的昆虫在其自然寿命的时间尺度上也会经历衰老。昆虫作为了解衰老的实验室系统的重要性，以及开发一种可以在现场和实验室研究的模型的潜力，使得了解野生昆虫的衰老成为一个令人兴奋的前景。我们将通过非常详细地监测野外蟋蟀的自然种群，对它们的衰老进行研究。我们会给每个人做DNA指纹和标记，然后用160个摄像机组成的网络一天24小时观察他们。这将使我们不仅可以测量寿命和繁殖，还可以收集详细的行为信息，使我们能够检测到在歌唱、洞穴周围运动、长距离运动、交配率、与其他个体战斗的成功率等特征上可能出现的微妙下降。通过将我们在这个项目中收集的数据与我们在过去6-8年收集的数据相结合，我们将解决一系列在野外很难回答的问题，因为其他研究没有我们拥有的详细信息：1。对衰老的主要进化解释是，个体的退化是因为他们在生命早期把所有的精力都投入到繁殖中，从而传递了更多的基因，即使这在以后的生活中付出了代价。我们将确定那些在早期繁殖中付出更多努力的个体，例如通过更多的交配，最终是否会衰退得更快。我们将确定环境条件是否会影响个体衰老的速度，以及由于气候和个体之间的竞争而压力更大的年份是否与更快的衰老有关。3. 据预测，雄性比雌性衰老得快，因为它们的繁殖速度并不受它们产卵速度的限制；所以它们更有可能在早期繁殖中投入大量资金，即使这会杀死它们。我们将观察男性是否比女性衰老得更快。雌性可能会从与年老的雄性交配中受益，因为它们的后代从能够存活很长时间的雄性身上获得基因。如果基因好的男性比基因差的男性衰老得慢，那么衰老将使老年男性选择女性更加有利。我们将测试具有其他优良基因迹象的男性是否也衰老得较慢。有人认为，不同的死亡来源将对衰老的演变产生不同的影响，这取决于个人是否可以在更好的条件下避免它们。我们将确定在这方面我国人口的死亡率来源是否有所不同。例如，你是否被一只知更鸟吃掉可能只是运气问题，而被另一只蟋蟀杀死可能取决于你保护自己的能力。

The study of why we, and all other living things, progressively deteriorate and become more likely to die as we get older is an issue of relevance to almost every other question in biology. However, the vast majority of ageing research is concerned with mechanistic explanations for declines in function. We have only really scratched the surface in terms of functional explanations for why ageing occurs in the first place, and we are even more in the dark in relation to how ageing proceeds in natural populations. We need to understand ageing in the wild, because it is clear that how ageing works in nature will affect the dynamics of key process such as sexual selection and the evolution of life-histories.Insects make up the vast majority of animal biodiversity and have been studied intensively in the lab, where they have become important model systems for understanding ageing. However, it seems very likely that when they are taken out of an environment where they have unlimited food and no parasites or predators, insects may show different patterns of senescence. It is now clear that even short lived insects experience senescence on the timescales of their natural life-spans. The importance of insects as laboratory systems for understanding ageing, and the potential for developing a model that can be studied in both field and lab makes understanding ageing in wild insects an exciting prospect. We will carry out a study of senescence in a natural population of field crickets by monitoring the population in great detail. We will DNA fingerprint and tag every individual, and then observe them 24 hrs a day using a network of 160 video cameras. This will enable us to not only measure lifespan and reproduction, but also to collect detailed behavioural information, allowing us to detect what may be quite subtle declines in performance in traits like singing, movement around their burrow, movement over longer distances, mating rate, success in fights with other individuals etc.By combining the data we will collect during this project with data we have collected over the previous 6-8 years, we will address a series of questions which have been very difficult to answer in the wild because other studies have not had the detailed information that we have:1. The main evolutionary explanation for ageing is that individuals deteriorate because they pass on more genes by putting all their energy into reproduction early in life even if this takes its toll later in life. We will determine whether individuals that put more effort into early reproduction, for instance by mating more, end up declining faster.2. We will determine whether environmental conditions affect how rapidly individuals age, and whether years which are more stressful due to climate and competition among individuals are associated with more rapid senescence. 3. Males have been predicted to age faster than females because their reproductive rate isn't capped by how fast they can lay eggs; so they have more potential to evolve to invest heavily in early reproduction even if it kills them. We will see if our males age faster than our females.4. Females may benefit from mating with old males because their offspring get genes from a male that was able to survive a long time. If males with good genes age slower than males with poorer genes then ageing will make female choice for old males even more beneficial. We will test whether males with other signs of good genes also age slower.5. It has been suggested that different sources of mortality will have different effects on the evolution of ageing depending on whether they can be avoided by individuals in better condition. We will determine whether the sources of mortality in our population vary in this respect. For instance, whether you get eaten by a robin may simply be a matter for luck, whereas being killed by another cricket may depend on how able you are to defend yourself.